Wind and Plants

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Wind and Plants
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WIND

• Wind has a major effect on agricultural and
  horticultural production in NZ.
• The prevailing winds are the most common winds in
  an area.
• NZ has a westerly wind pattern due to the earths
  spin. This is changed in some areas by local
  features and topography.
• The ranges to the north and the mountains to the
  sough turn the westerlies blowing towards
  Wellington into northerlies as they flow through
  Cook Strait.
• Strong moist northerly winds are common in
  Wellington in spring, these damage blossom and
  new plant growth.

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Wind

• Wind can be measured using the Beaufort scale.

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Effects of wind on plant productivity

• Structural damage
• Lodging flattening of cereal crops
• Cuticle damage on leaves increases water loss
• Broken branches
• Loss of petals on flowers
• Soil displacement causing soil erosion

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Physiological damage

• Removal of the layer of humid air around the
  leaves which forms a protective environment
• This causes

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Physiological damage

• Removal of the layer of humid air around the
  leaves which forms a protective environment
• This causes

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For each of the following problems, make notes on
why it is not good. Wind can cause many problems
including

• Increased erosion and removal of topsoil as
  dust. _

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• Lodging of plants (when leaves become entangled),
  making them difficult to harvest

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• Spreading weed seeds, meaning more costs of
  removal, or lower income due to contamination of
  seed crops.
• Reduced or damaged plant growth. Damaged leaves
  do not carry out as much photosynthesis. Flowers
  can be damaged or blown off the plant.
  Wind-damaged fruit does not store as well and is
  less marketable. Cuticle damage to leaves causes
  an increase in water loss.

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May bring salt spray or cause spray drift
Upsetting insect movement.
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Positive effects of the wind

• Reduced likelihood of frost
• Providing air movement that will dry the outer
  leaves of a plant and therefore prevent the
  growth of fungal diseases
• Assisting with the pollination of wind pollinated
  plants
• Aid the drying of hay or grains before harvest.

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Activity on wind page 45
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Correct order

• NZ is a fairly windy place
• Wind is caused by
• An anticyclone
• Near the Earths
• Over elevated

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Activity page 46
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Answers for pg 46

• Defoliation stripped of leaves
• Increased transpiration leaf scorching
• Abrasion sand particles
• Root damage plant rocking in ground
• Branches rub scarring on branches
• Plant distortion plant leaning away
• Lodging the flattening of cereal crops
• Reduction in pollination loss of petals

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• Fruit loss apple windfalls
• Fruit loss, knocked off tree pears downgraded
• Water loss wilting of plant
• Interference with insect movement bees cannot
  fly
• Crop maturation harvesting time later
• Spraying drifts from your property to another

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• Lessens humidity perfect disease free crop
• Reduces chance of frost Large open areas
• Increase in wind pollination grass pollen
• Guard cells the stomata changes shape

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Techniques to modify wind

• Artificial Shelter
• Artificial windbreaks are expensive to set up and
  are often used for high value or short term
  crops.
• The strongest likely wind has to be considered
  along with the soil type to prevent the support
  posts blowing over.

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Advantages

• a crop has instant shelter
• usually low maintenance
• takes up little space
• does not use up soil water and nutrients
• Does not have many of the disadvantages of live
  shelter

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Disadvantages

• require replacing after several years due to
  damage from light and wind
• not biodegradable creating disposal problems
• expensive
• Does not have many of the advantages of live
  shelter

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Wind Break Design

• 1. Permeable windbreaks are more effective at
  reducing the force of wind than a solid barrier.
• Live shelter should be triangular in vertical
  cross section this shape will reduce turbulence
  on the leeward side and cast less shadow.
• If the windbreak is impermeable, turbulence is a
• possibility on the leeward side.
• This is because the wind goes up and over the
  impermeable object.

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• 2. Areas with heavy snow drifts are protected by
  thicker shelter belts in the form of a small
  woodlot.
• 3. Distance between windbreaks should be no more
  than 20 times the height of the windbreak to
  prevent the build up of unsheltered windspeed.
• Large shelter is often planted around perimeters
  of blocks and subdivided with artificial shelter.

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• 4. Planting in double rows to allow
• reduction of draughts below taller shelter.
• replacement trees for older shelter belt.
• 5. In frost areas, where shelter is planted
  across valleys to prevent wind tunnelling, either
  deciduous shelter or gaps are used to allow cold
  air to drain away.

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• 6. Plant shelter across valleys to prevent wind
  tunnelling

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• 7. Run windbreaks north south where possible to
  reduce shading

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Student activities

• Page 88 - 89

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Answers to student activity

1. 14 at 8m
2. Air temp 16 at 1m, soil evap - -40 at 3m,
   relative humidity 8 at 1m, soil moisture 20
   at 1m, wind speed -60 at 4m
3. Air temp 2, soil evap -25, relat. Humid -0,
   soil moisture 3 and wind speed -45

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• 4.

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